Percutaneous radiofrequency ablation of hepatocellular carcinoma: fusion imaging guidance for management of lesions with poor conspicuity at conventional sonography. AJR Am J Roentgenol. 2012;198:1438-1444. [PMID: 22623560 DOI: 10.2214/ajr.11.7568]

Contribution and advances of robotics in percutaneous oncological interventional radiology

The advent of robotic systems in interventional radiology marks a significant evolution in minimally invasive medical procedures, offering enhanced precision, safety, and efficiency. This review comprehensively analyzes the current state and applications of robotic system usage in interventional radiology, which can be particularly helpful for complex procedures and in challenging anatomical regions. Robotic systems can improve the accuracy of interventions like microwave ablation, radiofrequency ablation, and irreversible electroporation. Indeed, studies have shown a notable decrease of an average 30% in the mean deviation of probes, and a 40% lesser need for adjustments during interventions carried out with robotic assistance. Moreover, this review highlights a 35% reduction in radiation dose and a stable-to-30% reduction in operating time associated with robot-assisted procedures compared to manual methods. Additionally, the potential of robotic systems to standardize procedures and minimize complications is discussed, along with the challenges they pose, such as setup duration, organ movement, and a lack of tactile feedback. Despite these advancements, the field still grapples with a dearth of randomized controlled trials, which underscores the need for more robust evidence to validate the efficacy and safety of robotic system usage in interventional radiology.

Local Ablation for Hepatocellular Carcinoma: 2024 Expert Consensus-Based Practical Recommendations of the Korean Liver Cancer Association

Local ablation for hepatocellular carcinoma, a non-surgical option that directly targets and destroys tumor cells, has advanced significantly since the 1990s. Therapies with different energy sources, such as radiofrequency ablation, microwave ablation, and cryoablation, employ different mechanisms to induce tumor necrosis. The precision, safety, and effectiveness of these therapies have increased with advances in guiding technologies and device improvements. Consequently, local ablation has become the first-line treatment for early-stage hepatocellular carcinoma. The lack of organized evidence and expert opinions regarding patient selection, preprocedure preparation, procedural methods, swift post-treatment evaluation, and follow-up has resulted in clinicians following varied practices. Therefore, an expert consensus-based practical recommendation for local ablation was developed by a group of experts in radiology and hepatology from the Research Committee of the Korean Liver Cancer Association in collaboration with the Korean Society of Image-Guided Tumor Ablation to provide useful information and guidance for performing local ablation and for the pre- and post-treatment management of patients.

Adjustable-tip needles versus fixed-tip needles in radiofrequency ablation of symptomatic benign thyroid nodules: a single-center Italian experience

PURPOSE

In this retrospective, observational study we aim to compare the outcomes of the RFA treatment of benign thyroid nodules, carried out respectively with the standard fixed-needle approach (FTN) and the adjustable-tip needle technique (ATN), considered a more tailored, quicker and easier technical approach.

METHODS

We enrolled 36 patients who underwent RFA treatment of symptomatic, benign, thyroid nodule, 18 with the ATN and 18 with the FTN approach, respectively. Data about absolute volume reduction, volume reduction rate (VRR) and success rate (defined as VRR ≥ 50%), after 1, 3 and 6 months of follow-up were compared.

RESULTS

Our study suggested no substantial difference between the approaches, up to 6 months of follow-up, both in terms of absolute reduction (p = 0.27) and VRR (p = 0.14). These results were confirmed when the success rates, both in terms of 50%-reduction (p = 0.12) and absolute reduction (p = 0.42), was considered. Only at the 6-month evaluation, the FTN procedure showed a better success rate, yet without statistical significance (88.9% vs. 61.1%, p = 0.12). No difference emerged both in terms of patients' satisfaction and safety.

CONCLUSION

Our small experience suggested no substantial difference between ATN and FTN, in terms of outcomes. On the other hand, ATN was considered to be more straightforward and could consequently allow for a shorter operator learning curve.

Local Ablation for Hepatocellular Carcinoma: 2024 Expert Consensus-Based Practical Recommendations of the Korean Liver Cancer Association

Local ablation for hepatocellular carcinoma (HCC), a non-surgical option that directly targets and destroys tumor cells, has advanced significantly since the 1990s. Therapies with different energy sources, such as radiofrequency ablation, microwave ablation, and cryoablation, employ different mechanisms to induce tumor necrosis. The precision, safety, and effectiveness of these therapies have increased with advances in guiding technologies and device improvements. Consequently, local ablation has become the first-line treatment for early-stage HCC. The lack of organized evidence and expert opinions regarding patient selection, pre-procedure preparation, procedural methods, swift post-treatment evaluation, and follow-up has resulted in clinicians following varied practices. Therefore, an expert consensus-based practical recommendation for local ablation was developed by a group of experts in radiology and hepatology from the Research Committee of the Korean Liver Cancer Association in collaboration with the Korean Society of Image-guided Tumor Ablation to provide useful information and guidance for performing local ablation and for the pre- and post-treatment management of patients.

Local ablation for hepatocellular carcinoma: 2024 expert consensus-based practical recommendation of the Korean Liver Cancer Association

Local ablation for hepatocellular carcinoma (HCC), a non-surgical option that directly targets and destroys tumor cells, has advanced significantly since the 1990s. Therapies with different energy sources, such as radiofrequency ablation, microwave ablation, and cryoablation, employ different mechanisms to induce tumor necrosis. The precision, safety, and effectiveness of these therapies have increased with advances in guiding technologies and device improvements. Consequently, local ablation has become the firstline treatment for early-stage HCC. The lack of organized evidence and expert opinions regarding patient selection, pre-procedure preparation, procedural methods, swift post-treatment evaluation, and follow-up has resulted in clinicians following varied practices. Therefore, an expert consensus-based practical recommendation for local ablation was developed by a group of experts in radiology and hepatology from the Research Committee of the Korean Liver Cancer Association in collaboration with the Korean Society of Image-guided Tumor Ablation to provide useful information and guidance for performing local ablation and for the pre- and posttreatment management of patients.

TACE-assisted multi-image guided radiofrequency ablation for the treatment of single hepatocellular carcinoma ≤ 5 cm: a retrospective study

Background/Objective

Treatment of hepatocellular carcinoma (HCC) with ablation alone often results in high rates of recurrence and metastasis, reaching up to 25.9% within two years. Therefore, this study aimed to examine the efficacy and safety of transarterial chemoembolization (TACE)-assisted multi-image guided radiofrequency ablation (RFA) for the treatment of stage Ia HCC according to the China liver cancer staging (CNLC).

Methods

This study enrolled and analyzed a total of 118 patients diagnosed with HCC, each with a single nodular lesion no larger than 5 cm, who received TACE-RFA as first-line therapy between February 1, 2014, and December 31, 2021. The median/mean follow-up period was 29.0 months [95% confidence interval (CI): 21.8-36.2 months] and 31.8 months (95% CI: 27.5-36.0 months), respectively. We assessed the treatment's effectiveness, potential complications, and survival rate.

Results

The technical success rate was 100% (118/118) after the initial treatment. Out of the total, 3 out of 118 patients (2.5%) developed local tumor progression (LTP) during the follow-up period. The median time for LTP was 29.0 months (95%CI: 21.9-36.1 months; mean: 31.5 months; range 1-92 months). At 1, 3, 5, and 7 years after treatment, the cumulative LTP rates were 0%, 4.6%, 4.6%, and 4.6%, respectively. The overall survival rates at 1, 3, 5, and 7 years were 100%, 95.2%, 95.2%, and 95.2%, respectively. In total, 28 patients experienced minor Grade B complications, and no major complications or treatment-related mortality occurred.

Conclusion

The treatment of CNLC stage Ia HCC using TACE-assisted multi-image-guided RFA was found to be both safe and feasible.

Three-dimensional ultrasound fusion imaging in precise needle placement for thermal ablation of hepatocellular carcinoma

PURPOSE

To investigate the value of three-dimensional ultrasound fusion imaging (3DUS FI) technique for guiding needle placement in hepatocellular carcinoma (HCC) thermal ablation.

METHODS

A total of 57 patients with 60 HCCs with 3DUS FI-guided thermal ablation were retrospectively included in the study. 3DUS volume data of liver were acquired preoperatively by freehand scanning with the tumor and predetermined 5 mm ablative margin automatically segmented. Plan of needle placement was made through a predetermined simulated ablation zone to ensure a 5 mm ablative margin with the coverage rate toward tumor and ablative margin. With real-time ultrasound and 3DUS fusion imaging, ablation needles were placed according to the plan. After ablation, the ablative margin was immediately evaluated by contrast-enhanced ultrasound and 3DUS fusion imaging. The rate of adequate ablative margin, complete response (CR), local tumor progression (LTP), disease-free survival (DFS), and overall survival (OS) was evaluated.

RESULTS

According to postoperative contrast-enhanced CT or MR imaging, the complete response rate was 100% (60/60), and 83% of tumors (30/36) achieved adequate ablative margin (>5 mm) three-dimensionally. During the follow-up period of 6.0-42.6 months, LTP occurred in 5 lesions, with 1- and 2-year LTP rates being 7.0% and 9.4%. The 1- and 2-year DFS rates were 76.1% and 65.6%, and 1- and 2-year OS rates were 98.1% and 94.0%. No major complications or ablation-related deaths were observed in any patients.

CONCLUSIONS

Three-dimensional ultrasound fusion imaging technique may improve the needle placement of thermal ablation for HCC and reduce the rate of LTP.

Contrast-enhanced ultrasonography-CT/MRI fusion guidance for percutaneous ablation of inconspicuous, small liver tumors: improving feasibility and therapeutic outcome

BACKGROUND

Percutaneous radiofrequency ablation (RFA) is pivotal for treating small malignant liver tumors, but tumors often remain inconspicuous on B-mode ultrasound (US). This study evaluates the potential of CEUS-CT/MRI fusion imaging (FI) to improve tumor visibility and the associated RFA outcomes for small (≤ 3 cm) malignant liver tumors that were inconspicuous on US.

METHODS

Between January 2019 and April 2021, a prospective study enrolled 248 patients with liver malignancies (≤ 3 cm) that were poorly visible on B-mode US. Tumor visibility and ablation feasibility were assessed using B-mode US, US-CT/MRI FI, and CEUS-CT/MRI FI, and graded on a 4-point scale. CEUS was employed post-registration of US and CT/MRI images, utilizing either SonoVue or Sonazoid. Comparisons between US-based and CEUS-based fusion visibility and feasibility scores were undertaken using the Friedman test. Moreover, rates of technical success, technique efficacy, local tumor progression (LTP), and major complications were assessed.

RESULTS

The cohort included 223 hepatocellular carcinomas (HCCs) (89.9%) and 23 metastases (9.3%), with an average tumor size of 1.6 cm. CEUS-CT/MRI FI demonstrated a significant advantage in tumor visibility (3.4 ± 0.7 vs. 1.9 ± 0.6, P < 0.001) and technical feasibility (3.6 ± 0.6 vs. 2.9 ± 0.8, P < 0.001) compared to US-FI. In 85.5% of patients, CEUS addition to US-FI ameliorated tumor visibility. Technical success was achieved in 99.6% of cases. No severe complications were reported. One and two-year post CEUS-CT/MRI FI-guided RFA estimates for LTP were 9.3% and 10.9%, respectively.

CONCLUSIONS

CEUS-CT/MRI FI significantly improves the visualization of tumors not discernible on B-mode US, thus augmenting percutaneous RFA success and delivering improved therapeutic outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT05445973. Registered 17 June 2022 - Retrospectively registered, http://clinicaltrials.gov/study/NCT05445973?id=NCT05445973&rank=1 .

Clinical Impact of a Protocol Involving Cone-Beam CT (CBCT), Fusion Imaging and Ablation Volume Prediction in Percutaneous Image-Guided Microwave Ablation in Patients with Hepatocellular Carcinoma Unsuitable for Standard Ultrasound (US) Guidance

PURPOSE

to evaluate the clinical impact of a protocol for the image-guided percutaneous microwave ablation (MWA) of hepatocellular carcinoma (HCC) that includes cone-beam computed tomography (CBCT), fusion imaging and ablation volume prediction in patients with hepatocellular carcinoma unsuitable for standard ultrasound (US) guidance.

MATERIALS AND METHODS

this study included all patients with HCC treated with MWA between January 2021 and June 2022 in a tertiary institution. Patients were divided into two groups: Group A, treated following the protocol, and Group B, treated with standard ultrasound (US) guidance. Follow-up images were reviewed to assess residual disease (RD), local tumor progression (LTP) and intrahepatic distant recurrence (IDR). Ablation response at 1 month was also evaluated according to mRECIST. Baseline variables and outcomes were compared between the groups. For 1-month RD, propensity score weighting (PSW) was performed.

RESULTS

80 consecutive patients with 101 HCCs treated with MWA were divided into two groups. Group A had 41 HCCs in 37 patients, and Group B had 60 HCCs in 43 patients. Among all baseline variables, the groups differed regarding their age (mean of 72 years in Group A and 64 years in Group B, respectively), new vs. residual tumor rates (48% Group A vs. 25% Group B, p < 0.05) and number of subcapsular tumors (56.7% Group B vs. 31.7% Group A, p < 0.05) and perivascular tumors (51.7% Group B vs. 17.1% Group A, p < 0.05). The protocol led to repositioning the antenna in 49% of cases. There was a significant difference in 1-month local response between the groups measured as the RD rate and mRECIST outcomes. LTP rates at 3 and 6 months, and IDR rates at 1, 3 and 6 months, showed no significant differences. Among all variables, logistic regression after PSW demonstrated a protective effect of the protocol against 1-month RD.

CONCLUSIONS

The use of CBCT, fusion imaging and ablation volume prediction during percutaneous MWA of HCCs provided a better 1-month tumor local control. Further studies with a larger population and longer follow-up are needed.

Petre E, Marinelli B, Sarkar D, Barral M, H Cornelis F. Percutaneous liver interventions with robotic systems: a systematic review of available clinical solutions

OBJECTIVE

Robotic-guided interventions are emerging techniques that are gradually becoming a common tool for performing biopsies and tumor ablations in liver. This systematic review aims to evaluate their advancements, challenges, and outcomes.

METHODS

A systematic review was conducted using the PubMed database to identify relevant articles published between January 2000 and February 2023. Inclusion criteria focused on studies that assessed robotic systems for percutaneous liver biopsies and tumor ablations. Data extraction was performed to collect information on study characteristics; robotic systems; components and software; imaging modality; degree of freedom; and needle insertion methods. The outcome measures analyzed were procedure time, radiation dose, and accuracy.

RESULTS

10 studies met the inclusion criteria. The robotic devices used included MAXIO, EPIONE, ROBIO-EX, AcuBot, and ACE robotic systems. The data set consisted of 429 percutaneous thermal ablations and 57 biopsies, both robot-guided. On average, the mean deviation of probes was reduced by 30% (from 1.6 vs 3.3 mm to 2.4 vs 3.9 mm (p < 0.001)), and 40% (p < 0.05) fewer readjustments were required during the robotic-assisted interventions. Moreover, robotic systems contributed to a reduction in operating time, ranging from 15% (18.3 vs 21.7 min, p < 0.001) to 25% (63.5 vs 87.4 min, p < 0.001). Finally, the radiation dose delivered to both the patient and the operator was decreased by an average of 50% (p < 0.05) compared to manual procedures.

ADVANCES IN KNOWLEDGE

Robotic systems could provide precise navigation and guidance during liver biopsies and percutaneous ablations.

Tips for Preparing and Practicing Thermal Ablation Therapy of Hepatocellular Carcinoma

Thermal ablation therapy, including radiofrequency ablation (RFA) and microwave ablation (MWA), is considered the optimal locoregional treatment for unresectable early-stage hepatocellular carcinomas (HCCs). Percutaneous image-guided ablation is a minimally invasive treatment that is being increasingly performed because it achieves good clinical outcomes with a lower risk of complications. However, the physics and principles of RFA and MWA markedly differ. Although percutaneous thermal ablation under image guidance may be challenging in HCC cases with limited access or a risk of thermal injury, a number of ablative techniques, each of which may be advantageous and disadvantageous for individual cases, are available. Furthermore, even when a HCC is eligible for ablation based on tumor selection and technical factors, additional patient factors may have an impact on whether it is the appropriate treatment choice. Therefore, a basic understanding of the advantages and limitations of each ablation device and imaging guidance technique, respectively, is important. We herein provide an overview of the basic principles of tissue heating in thermal ablation, clinical and laboratory parameters for ablation therapy, preprocedural management, imaging assessments of responses, and early adverse events. We also discuss associated challenges and how they may be overcome using optimized imaging techniques.

Usefulness of ultrasound fusion technology for hepatocellular carcinoma localisation, pre- and post-thermal ablation

INTRODUCTION

Percutaneous thermal ablation of inconspicuous lesions can be challenging. Fusion ultrasound (FUS) allows the use of previously performed diagnostic imaging like computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET-CT) to localise hepatocellular carcinoma (HCC) for treatment. This paper illustrates FUS case studies of pre-, intra- and post-ablation imaging of inconspicuous HCC, supplemented by use of contrast-enhanced ultrasound (CEUS).

METHOD

Four prospective cases during September 2014 to October 2018, with HCC amenable to ablation, which were poorly identified on ultrasound, underwent FUS. FUS pre-screening was scheduled within three months of the previous CT or MRI, and between one to four weeks prior to the scheduled ablation date. Post-ablation imaging with FUS was performed between four to six weeks to coincide with their routine follow-up CT or MRI.

FINDINGS

There were potential benefits observed in the cases with combined techniques of FUS and CEUS for limiting circumstances such as heat sink effect, multiple lesions targeting, inconspicuous lesion detection and pre-ablation technical feasibility assessment.

DISCUSSION

The combined use of FUS and CEUS improves tumour visibility, increases operator imaging confidence and reduces heat sink effect during percutaneous thermal ablation.

CONCLUSION

FUS imaging is helpful in targeting poor conspicuity lesions that cannot be detected on grey-scale ultrasound. It facilitates in ensuring optimal treatment of hepatic lesions for improvement of patient prognosis and follow-up imaging.

Advances in the interventional therapy of hepatocellular carcinoma originating from the caudate lobe

Hepatocellular carcinoma originating from the caudate lobe, also known as segment I hepatocellular carcinoma, is difficult to treat because of its special location, complex vascular supply, and the proximity of important vessels, bile ducts, and organs. This research is conducted to examine the efficacy and safety of interventional therapy for hepatocellular carcinoma in the caudate lobe.

Conclusion

Superselective chemoembolization and ablation techniques for the treatment of caudate lobe hepatocellular carcinoma still need to be improved. The combination of multiple interventional methods and the application of multiple imaging techniques can improve the effectiveness and safety of interventional therapy for hepatocellular carcinoma in the caudate lobe. Multidisciplinary treatment is also essential to improve the prognosis of patients with caudate lobe hepatocellular carcinoma.

•

The anatomical characteristics of the arteries in the caudate lobe hepatocellular carcinoma remains an important factor restricting the success rate of superselective transcatheter arterial chemoembolization.

•

The application of multiple imaging techniques may improve the effectiveness and safety of interventional therapy.

•

The combination of multiple interventional methods has more advantages than disadvantages.

•

Multidisciplinary treatment is increasingly becoming a trend in the treatment of caudate lobe hepatocellular carcinoma.

Iodized oil computed tomography versus ultrasound-guided radiofrequency ablation for early hepatocellular carcinoma

BACKGROUND AND PURPOSE

Radiofrequency ablation (RFA) is the standard of care for early stage hepatocellular carcinoma (HCC). However, the clinical outcomes of iodized oil computed tomography (IoCT) versus ultrasound (US)-guided RFA for HCC remain unclear.

METHODS

We retrospectively analyzed consecutive treatment-naïve patients who received curative RFA for HCC within Milan criteria from January 2016 to December 2018. Patients who underwent either IoCT-guided RFA (IoCT group) or US-guided RFA (US group) were included. Various clinical factors, including tumor location, were adjusted with a 1:1 propensity score matching. Subsequently, the cumulative incidence rates for recurrence and hazard ratios for survival were calculated.

RESULTS

We included 184 (37.9%) and 301 (62.1%) patients who received IoCT- and US-guided RFA, respectively. Before propensity score matching, IoCT guidance was significantly associated with multiple tumors, higher body mass index, lower albumin level, and tumors located at S8. After matching, the 1-, 2-, and 3-year local tumor progression rates of the IoCT group were significantly lower than those of the US group (4.4%, 6.9%, and 7.5% vs. 14.4%, 16.3%, and 16.3%, respectively, at p = 0.002, 0.009, and 0.016, respectively). In univariate analyses and multivariate analyses that adjusted for clinical and tumor location-related parameters, the IoCT group had better recurrence-free survival (hazard ratio = 0.581, 95% confidence interval 0.375-0.899) than those with US guidance but not overall survival.

CONCLUSION

IoCT-guided RFA had a lower local tumor progression rate and better recurrence-free survival than did US-guided RFA for HCC within the Milan criteria. CT-guide RFA is a safe and effective alternative to US-guided with similar overall survival. IoCT-guided RFA might have a better local tumor control than US-guided. IoCT-guided RFA may be more suitable for male patients, aged < 70 years, a single tumor measuring 2-5 cm, and a tumor located at the subdiaphragmatic/subcardiac region.

Utility of Real-time CT/MRI-US Automatic Fusion System Based on Vascular Matching in Percutaneous Radiofrequency Ablation for Hepatocellular Carcinomas: A Prospective Study

PURPOSE

To prospectively evaluate the technical success rate of real-time computed tomography/magnetic resonance imaging and ultrasound (CT/MRI-US) automatic fusion system and the long-term therapeutic efficacy of radiofrequency ablation (RFA) guided by automatic fusion in hepatocellular carcinoma (HCC) patients.

MATERIALS AND METHODS

139 patients with 151 HCCs were prospectively enrolled for RFA guided by an automatic CT/MRI-US fusion system (PercuNav system, Philips, the Netherlands). Automatic fusion imaging, based on vascular segmentation and registration, was performed by sonographic sweeping at the intercostal plane. The fusion quality, tumor localization confidence and technical feasibility were recorded before and after fusion using a scoring system. Technical success rate of the RFA procedure and local tumor progression (LTP) were assessed during follow-up. Analysis of technical success and LTP was performed using generalized estimating equations and Cox proportional hazard regression analysis.

RESULTS

The success rate of the fusion system was 82.7% (115/139) per patient. The mean sonographic scan time for fusion was 154.4 ± 108.4 s. In patients with successful fusion, the score indicating tumor localization confidence (2.2 ± 0.8 vs. 2.7 ± 0.9) and technical feasibility (2.6 ± 0.8 vs. 3.4 ± 0.7) increased after fusion (p < 0.001). The technical success rate of the RFA procedure was 96.8% (120/124) per tumor in patients with successful fusion, including poorly localized tumors. LTP rates were 8.6%, 12.2% and 15.2% at 1, 2 and 3 years.

CONCLUSION

The CT/MRI-US automatic fusion system showed a high success rate for image registration and facilitated better feasibility and a high technical success rate of RFA in HCCs, even with poor localization on US.

LEVEL OF EVIDENCE

Level 3b, Nonrandomized prospective study.

Assessing the value of volume navigation during ultrasound-guided radiofrequency- and microwave-ablations of liver lesions

Purpose

The goal of our study was to determine the influence of ultrasound (US)-coupled volume navigation on the use of computed tomography (CT) during minimally-invasive radiofrequency and microwave ablation procedures of liver lesions.

Method

Twenty-five patients with 40 liver lesions of different histological origin were retrospectively analysed. Lesions were ablated following standard protocol, using 1) conventional US-guidance, 2) manual registered volume navigation (mVNav), 3) automatic registered (aVNav) or 4) CT-guidance. In case of ultrasonographically inconspicuous lesions, conventional US-guidance was abandoned and mVNav was used. If mVNav was also unsuccessful, the procedure was either continued with aVNav or CT-guidance. The number, size and location of the lesions targeted using the different approaches were documented.

Results

Of the 40 lesions, sixteen (40.0 %) could be targeted with conventional US-guidance only, sixteen (40.0 %) with mVNav, three (7.5 %) with aVNav and five (12.5 %) only through the use of CT-guidance. Of the three alternatives (mVNav, aVNav and CT only) the mean size of the lesions targeted using mVNav (9.1 ± 4.6 mm) was significantly smaller from those targeted using US-guidance only (20.4 ± 9.4 mm; p < 0.001). The location of the lesions did not influence the selection of the modality used to guide the ablation.

Conclusions

In our cohort, mVNav allowed the ablation procedure to become less dependent on the use of CT. mVNav supported the ablation of lesions smaller than those that could be ablated with US only and doubled the application of minimally-invasive US-guided ablations.

Challenges Facing Percutaneous Ablation in the Treatment of Hepatocellular Carcinoma: Extension of Ablation Criteria

As an emerging minimally invasive treatment method, percutaneous ablation is more and more widely used in the treatment of liver tumors. It has been recommended by guidelines for diagnosis and treatment of hepatocellular carcinoma (HCC) as a curative treatment alongside surgical resection and liver transplantation. In recent years, with the continuous advancement and innovation of percutaneous ablation technologies, their clinical efficacy and safety have been significantly improved, which has led to the expanded application of percutaneous ablation in the treatment of HCC—more and more patients who were previously considered unsuitable for ablation therapies are now being treated with percutaneous ablation. Obviously, percutaneous ablation can reduce the risk of treatment changes from curative strategies to palliative strategies. Based on clinical practice experience, this review enumerates the advantages and disadvantages of different ablative modalities and summarizes the existing combinations of ablation techniques, thus will help clinicians choose the most appropriate ablative modality for each patient and will provide scientific guidance for improving prognosis and making evidence-based treatment decisions. In addition, we point out the challenges and future prospects of the ablation therapies, thereby providing direction for future research.

Utility of real-time image fusion technology in ultrasonography-guided fiducial marker implantation for stereotactic body radiation therapy for liver tumors

BACKGROUND

Ultrasonography (US) is useful when implanting fiducial markers in the liver. However, the implant position is sometimes lost. Recently, real-time image fusion technology (Volume Navigation [V-navi]; GE Healthcare, Milwaukee, WI, USA) has been introduced as a technique for using images from different modalities, and its utility for fiducial marker implantation has been hypothesized.

PURPOSE

To evaluate the utility of US-guided fiducial marker implantation in the liver using V-navi compared to conventional US.

MATERIAL AND METHODS

We retrospectively reviewed 35 patients who underwent fiducial marker implantation for stereotactic body radiation therapy of liver tumors in 2013-2018. To avoid artifacts obscuring the tumor, the target point of implantation was set 10 mm cranial or caudal to the tumor. Marker implantation was then performed using US alone (US group, n = 24) or V-navi with computed tomography (CT) or magnetic resonance imaging (V-navi group, n = 11). Postprocedural CT was evaluated to determine technical success, distances between marker and either tumor surface or target point, and whether marker-induced artifacts obscured the tumor. Complications were also evaluated. Results were compared between groups.

RESULTS

Technical success was obtained in 33 patients. Distance between the tumor and marker showed no significant difference between groups. Distance between target point and marker was shorter in the V-navi group (P = 0.0093). Tumor-obscuring artifacts were seen in 12 patients (V-navi group, n = 1; US group, n = 11; P = 0.055). The only complication was minor bleeding in the US group (n = 1).

CONCLUSION

V-navi appears useful for US-guided fiducial marker implantation in the liver compared with conventional US.

Percutaneous Irreversible Electroporation for Treatment of Small Hepatocellular Carcinoma Invisible on Unenhanced CT: A Novel Combined Strategy with Prior Transarterial Tumor Marking

INTRODUCTION

To explore the feasibility, safety, and efficiency of ethiodized oil tumor marking combined with irreversible electroporation (IRE) for small hepatocellular carcinomas (HCCs) that were invisible on unenhanced computed tomography (CT).

METHODS

A retrospective analysis of the institutional database was performed from January 2018 to September 2018. Patients undergoing ethiodized oil tumor marking to improve target-HCC visualization in subsequent CT-guided IRE were retrieved. Target-HCC visualization after marking was assessed, and the signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNR) were compared between pre-marking and post-marking CT images using the paired t-test. Standard IRE reports, adverse events, therapeutic endpoints, and survival were summarized and assessed.

RESULTS

Nine patients with 11 target-HCCs (11.1-18.8 mm) were included. After marking, all target-HCCs demonstrated complete visualization in post-marking CT, which were invisible in pre-marking CT. Quantitatively, the SNR of the target-HCCs significantly increased after marking (11.07 ± 4.23 vs. 3.36 ± 1.79, p = 0.006), as did the CNR (4.32 ± 3.31 vs. 0.43 ± 0.28, p = 0.023). In sequential IRE procedures, the average current was 30.1 ± 5.3 A, and both the delta ampere and percentage were positive with the mean values of 5.8 ± 2.1 A and 23.8 ± 6.3%, respectively. All procedures were technically successful without any adverse events. In the follow-up, no residual unablated tumor (endpoint-1) was observed. The half-year, one-year, and two-year local tumor progression (endpoint-2) rate was 0%, 9.1%, and 27.3%. The two-year overall survival rate was 100%.

CONCLUSIONS

Ethiodized oil tumor marking enables to demarcate small HCCs that were invisible on unenhanced CT. It potentially allows a safe and complete ablation in subsequent CT-guided IRE.

Immediate post-interventional contrast-enhanced computed tomography overestimates hepatic microwave ablation - an in vivo animal study

Objectives: Contrast-enhanced computed tomography (CECT) is used to monitor technical success immediately after hepatic microwave ablation (MWA). However, it remains unclear, if CECT shows the exact extend of the thermal destruction zone, or if tissue changes such as peri-lesionary edema are depicted as well. The objective of this study was to correlate immediate post-interventional CECT with histological and macroscopic findings in hepatic MWA in porcine liver in vivo.Methods: Eleven MWA were performed in porcine liver in vivo with a microwave generator (928 MHz; energy input 24 kJ). CECT was performed post-interventionally. Livers were explanted and ablations were bisected immediately after ablation. Samples were histologically analyzed after vital staining (NADH-diaphorase). Ablation zones were histologically and macroscopically outlined. We correlated histologic findings, macroscopic images and CECT.Results: Three ablation zones were identified in histological and macroscopic findings. Only one ablation zone could be depicted in CECT. Close conformity was observed between histological and macroscopic findings. The ablation zone depicted in CECT overestimated the histological avital central zone and inner red zone (p < = .01). No differences were found between CECT and the histological outer red zone (p > .05).Conclusions: Immediate post-interventional CECT overestimated the clinically relevant zone of complete cell ablation after MWA in porcine liver in vivo. This entails the risk of incomplete tumor ablation and could lead to tumor recurrence.

Repeat hepatic resection VS radiofrequency ablation for the treatment of recurrent hepatocellular carcinoma: an updated meta-analysis

BACKGROUND

This paper evaluates the efficacy and safety of repeat hepatic resection and radiofrequency ablation in the treatment of recurrent hepatocellular carcinoma.

MATERIAL AND METHODS

We retrieved and collected all relevant articles from the inception to 8 March 2020. After data extraction, we conducted meta-analysis and carried out the heterogeneity test, sensitivity analysis, and publication bias test to evaluate reliability.

RESULTS

A total of 12 studies with 1746 patients (rHR 837, RFA 909) were included. rHR was similar to RFA in a one-year overall survival rate (OS), while rHR was superior to RFA in 3- and 5-year OS and 1-, 3-, and 5-year disease-free survival rates (DFS), but the procedure-related complications of RFA were significantly less than those of rHR. Among the subgroups with Milan criteria, rHR was similar to RFA in 1-, 3-, and 5-year OS and 1-year DFS, but superior to RFA in 3- and 5-year DFS.

CONCLUSIONS

RFA is the first choice for recurrent HCC meeting Milan criteria. When it does not meet the Milan criteria, minimally invasive treatment should not be carried out at the cost of survival, and rHR should be the first choice.

SN, Kulkarni S, Shetty NS, Gupta A, Gupta S. Indian Society of Vascular and Interventional Radiology Expert Consensus Statements for Ablation in Hepatocellular Carcinoma: Part I

Locoregional therapies play an important role in the management of hepatocellular carcinoma (HCC). Percutaneous ablation is one of the most commonly employed nonsurgical methods for treating very early and early HCC. For small HCCs, ablation is potentially curative and competes with surgical resection. The widespread availability and the spectrum of ablative techniques mandate uniform approach among interventional radiologists. Thus, it is desirable to have a consensus regarding various aspects of liver ablation. This article represents a consensus document of the experts from the Indian Society of Vascular and Interventional Radiology involved in the care of patients with HCC. The statements are presented in two parts.

Locoregional Therapy Approaches for Hepatocellular Carcinoma: Recent Advances and Management Strategies

Hepatocellular carcinoma (HCC) is the most common primary liver malignancy and third leading cause of cancer-related mortality worldwide. While surgical resection and transplantation are the standard first-line treatments for early-stage HCC, most patients do not fulfill criteria for surgery. Fortunately, catheter-directed and percutaneous locoregional approaches have evolved as major treatment modalities for unresectable HCC. Improved outcomes have been achieved with novel techniques which can be employed for diverse applications ranging from curative-intent for small localized tumors, to downstaging or bridging to resection and transplantation for early and intermediate disease, and locoregional control and palliation for advanced disease. This review explores recent advances in liver-directed techniques for HCC including bland transarterial embolization, chemoembolization, radioembolization, and ablative therapies, with a focus on patient selection, procedural technique, periprocedural management, and outcomes.

Manual versus automated image fusion of real-time ultrasonography and MR/CT images for radiofrequency ablation of hepatic tumors: results of a randomized prospective trial (NCT02705118)

PURPOSE

This study compared the technical parameters and clinical outcomes of manual and automatic image fusion techniques of ultrasonography and magnetic resonance imaging/computed tomography for radiofrequency ablation (RFA) of hepatic tumors.

METHODS

Seventy consecutive patients (male:female=47:23, 67.1±10.9 years old) who underwent RFA for hepatic tumors were prospectively enrolled and randomly assigned to the manual or automatic registration group. Two operators performed RFA with one of two imaging fusion techniques. Technical parameters (the registration error, time required for image registration, number of point registrations) and clinical outcomes (technical success, technical effectiveness, local tumor progression [LTP]-free survival, and progression-free survival [PFS]) were compared.

RESULTS

The automatic group contained 35 patients with hepatocellular carcinoma, while the manual group included 34 hepatocellular carcinoma patients and a patient with colon cancer liver metastasis. The registration error, time required for registration, and number of point registrations were 5.7±4.3 mm, 147.8±78.2 seconds, and 3.26±1.20 in the automatic group, and 6.3±5.0 mm, 150.3±89.7 seconds, and 3.20±1.13 in the manual group, respectively. The technical success and effectiveness rates were both 97.1% in the automatic group and both 100.0% in the manual group. The above differences were not significant. The LTP-free survival and PFS (28.3 and 21.2 months in the automatic group, and 29.0 and 24.9 months in the manual group, respectively) showed no significant between-group differences during a median 20.1-month follow-up period.

CONCLUSION

The technical parameters and clinical outcomes of automatic image fusion were not significantly different from those of manual image fusion for RFA of hepatic tumors.

The AFSUMB Consensus Statements and Recommendations for the Clinical Practice of Contrast-Enhanced Ultrasound using Sonazoid

The first edition of the guidelines for the use of ultrasound contrast agents was published in 2004, dealing with liver applications. The second edition of the guidelines in 2008 reflected changes in the available contrast agents and updated the guidelines for the liver, as well as implementing some nonliver applications. The third edition of the contrast-enhanced ultrasound (CEUS) guidelines was the joint World Federation for Ultrasound in Medicine and Biology-European Federation of Societies for Ultrasound in Medicine and Biology (WFUMB-EFSUMB) venture in conjunction with other regional US societies such as Asian Federation of Societies for Ultrasound in Medicine and Biology, resulting in a simultaneous duplicate on liver CEUS in the official journals of both WFUMB and EFSUMB in 2013. However, no guidelines were described mainly for Sonazoid due to limited clinical experience only in Japan and Korea. The new proposed consensus statements and recommendations provide general advice on the use of Sonazoid and are intended to create standard protocols for the use and administration of Sonazoid in hepatic and pancreatobiliary applications in Asian patients and to improve patient management.

The AFSUMB Consensus Statements and Recommendations for the Clinical Practice of Contrast-Enhanced Ultrasound using Sonazoid

The first edition of the guidelines for the use of ultrasound contrast agents was published in 2004, dealing with liver applications. The second edition of the guidelines in 2008 reflected changes in the available contrast agents and updated the guidelines for the liver, as well as implementing some nonliver applications. The third edition of the contrast-enhanced ultrasound (CEUS) guidelines was the joint World Federation for Ultrasound in Medicine and Biology-European Federation of Societies for Ultrasound in Medicine and Biology (WFUMB-EFSUMB) venture in conjunction with other regional US societies such as Asian Federation of Societies for Ultrasound in Medicine and Biology, resulting in a simultaneous duplicate on liver CEUS in the official journals of both WFUMB and EFSUMB in 2013. However, no guidelines were described mainly for Sonazoid due to limited clinical experience only in Japan and Korea. The new proposed consensus statements and recommendations provide general advice on the use of Sonazoid and are intended to create standard protocols for the use and administration of Sonazoid in hepatic and pancreatobiliary applications in Asian patients and to improve patient management.

Electromagnetic tracking-based ultrasound/computed tomography fusion imaging in dogs: preliminary application to ocular and periocular regions

In ultrasound/computed tomography (CT) fusion images, ultrasound allows visualization of the target in real time. CT provides a navigation for ultrasound scanning and improves the overview in areas of limited visualization with ultrasound. This study was performed to investigate the feasibility of ultrasound/CT fusion based on an electromagnetic tracking technique using external fiducial markers for canine ocular and periocular regions. In 7 Beagle dogs, contrast-enhanced CT images of the head were obtained with placing external fiducial markers over the frontal region and both sides of the forepaws of the dog. Ultrasonography was performed under a magnetic field by installing a position sensor in the linear probe, without changing the dog's position. The positions of the external fiducial markers were adjusted and matched, based on the CT images. The execution time of co-registration and the distance between the regions of interest and the co-registration points, the frontal bone, cornea, retina, and optic nerve, were estimated. Approximately 60% of external fiducial markers were properly recognized in all dogs. After adjustment, all external fiducial markers were precisely matched. The co-registration execution time was less than 1 min. The distances between the regions of interest and co-registration points were less than 3 mm in all dogs. The electromagnetic tracking technique using external fiducial markers was a simple and applicable method for fusion imaging of a canine head using real-time ultrasonography and CT. This technique can be useful for interventional procedures of retrobulbar and periorbital lesions.

Complications after Radiofrequency Ablation for Hepatocellular Carcinoma: A Multicenter Study Involving 9,411 Japanese Patients

INTRODUCTION

Radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC) is considered a safe and minimally invasive procedure. We previously reported that the mortality and complication rates for RFA were 0.038% (5/13,283 patients) and 3.54% (579 complications/16,346 procedures), respectively, from 1999 to 2010 (previous period). In this study, we investigated the clinical criteria for RFA and the mortality and complication rates from 2011 to 2015 (recent period).

METHODS

Data were collected from 25 centers by using a questionnaire developed by the Chugoku-Shikoku Society for Local Ablation Therapy of HCC. The criteria for RFA, RFA modification, use of image-guidance modalities, mortality, and complications during the previous and recent periods were compared.

RESULTS

We evaluated 11,298 procedures for 9,411 patients, including those that involved new devices (bipolar RFA and internally adjustable electrode system). The criterion of hepatic function for RFA increased from a Child-Pugh score ≤8 during the previous period to ≤9 during the recent period. The criteria regarding the tumor location and other risk factors have been expanded recently because of the increased use of several modifications of the RFA procedure and image-guidance modalities. The mortality rate was 0.064% (6/9,411 patients), and the complication rate was 2.92% (330 complications/11,298 procedures). There was no difference in mortality rates between the 2 periods (p = 0.38), but the complication rates was significantly lower during the recent period (p = 0.038).

DISCUSSION AND CONCLUSIONS

Our findings confirmed that RFA, including the use of new devices, is a low-risk procedure for HCC, despite the expansion of the criteria for RFA during the recent period.

Feasibility of supine MRI (Magnetic Resonance Imaging)-navigated ultrasound in breast cancer patients

OBJECTIVE

The purpose of this study was to evaluate the feasibility of image fusion between US and supine MRI in breast cancer patients, and to evaluate differences in tumor location between prone and supine positions.

METHODS

This prospective study included 88 patients who underwent an additional supine MRI (MRsup) sequence following routine prone MRI (MRpro) for breast cancer between May 2016 and December 2017. The location of the tumor and discrepancies in the distances from nipple to lesion (NLD), skin to lesion (SLD), and chest wall to lesion (CLD) were evaluated between MRpro and MRsup (MRpro-sup), MRpro and MRsup-navigated US (MRpro-USnav), and MRsup and USnav (MRsup-USnav). Associations between breast thickness and measurement discrepancies were analyzed.

RESULTS

Total 91 index lesions were evaluated. The intraclass correlation coefficients (ICCs) for the location of MRpro and MRsup compared with USnav were 0.994 (range: 0.990-0.996) and 0.998 (range: 0.996-0.999), respectively. The mean MRpro-sup and MRpro-USnav measurement discrepancies were greater than those of MRsup-USnav, significantly. Most outer locations showed greater mean measurement discrepancies than inner locations, and each NLD, SLD, and CLD mean measurement discrepancy showed different tendencies according to location (upper or lower) and lesion depth (superficial, middle, or deep). High breast thickness showed significantly greater mean measurement discrepancies than low breast thickness.

CONCLUSION

Image fusion between US and supine MRI is feasible in breast cancer patients, although there is a considerable difference in tumor location measurements between prone and supine positions, especially with thicker breasts.

The use of image fusion in prenatal medicine

Fusion imaging (FI), the simultaneous display of the same anatomical region using two imaging modalities, has been used in other areas of medicine for both diagnosis and guiding interventions. Examples include positron emission tomography-computed tomography (PET-CT) imaging in oncology and ultrasound-magnetic resonance imaging (US-MRI) fusion in biopsies of the prostate gland. The underlying principle is to take advantage of the complementary information in each modality to improve accuracy, be it diagnostic accuracy or targeting accuracy in biopsies. For example, PET-CT overlays the metabolic activity of lesions on the superb spatial and anatomical detail of CT. While the historical mainstay of fetal imaging has been ultrasound, advances in ultrafast MR imaging together with advances in fetal MRI over the past two decades, have resulted in the opportunity to explore fusion imaging in fetal medicine. We present an overview of the principles of US-MRI fusion imaging in prenatal medicine, report our local experience, and review the literature in this emerging area. We share our perspective on how FI can improve diagnostic confidence, be used as an educational tool, and potentially enhance guidance in certain fetal procedures.

Thermal ablation with fusion imaging guidance of hepatocellular carcinoma without conspicuity on conventional or contrast-enhanced US: surrounding anatomical landmarks matter

AIM

Evaluating clinical and technical factors affecting thermal ablation of B-Mode/CEUS inconspicuous HCC nodules, relying only on fusion imaging (FI) performed under conscious sedation and using previously acquired CT or MR.

MATERIALS AND METHODS

Among 367 HCC nodules treated in the study period, data of 37 B-mode/CEUS undetectable HCC nodules treated with FI-guided ablation were extracted from our prospectively collected institutional database. Analyzed variables included patients' sex, age, cirrhosis etiology, Child-Pugh status, size of the lesion, liver segment, subcapsular or central liver site, type of imaging used for fusion (MR/CT), and the presence of surrounding anatomical landmarks (SAL) < 3 cm from the index lesion.

RESULTS

The primary efficacy was 59.4% (22/37 nodules); nine lesions (24.3%) were partially ablated (PA), six lesions (16.7%) were mistargeted (MA). Eight nodules were retreated with a CA obtained in all cases (100% CA, secondary efficacy in 30/37-81.1%). LTP was observed in 2/30 cases (6.7%). Two minor complications were registered (Clavien-Dindo, Grade1, CIRSE Classification Grade 2). SAL were related to a better ablation outcome (37.5% vs 84.6% p = 0.01). No differences were observed between CA group and PA-MA group in terms of lesion size (15.4 mm vs 14.9 mm p = 0.63), liver segment (p = 0.58), subcapsular or central liver site (8/22 36% vs 4/15 26.7% p = 0.84), and imaging (MR vs CT, p = 0.72).

CONCLUSION

Even in the presence of potentially critical conditions (completely B-Mode/CEUS inconspicuous nodules, spontaneous breathing, and previously acquired CT or MRI), FI-only guidance is safe and allows having good primary, secondary efficacy and LTP rates. The outcome of the procedure is heavily affected by the presence of SAL.

Intraprocedural computed tomography/magnetic resonance-contrast-enhanced ultrasound fusion imaging improved thermal ablation effect of hepatocellular carcinoma: Comparison with conventional ultrasound

AIM

To retrospectively compare the treatment effect of intraprocedural computed tomography/magnetic resonance-contrast-enhanced ultrasound (CT/MR-CEUS) fusion imaging (FI) with that of conventional ultrasound (US) in the guidance and assessment of thermal ablation of hepatocellular carcinoma (HCC).

METHODS

The FI group (112 patients with 129 HCC) was treated between April 2010 and December 2012, whereas the US group (83 patients with 90 HCC) was treated between January 2008 and March 2010. Either CT/MR-CEUS FI or US was used to guide puncture, provide immediate assessment, and guide supplementary ablation. Technical efficacy, cumulative local tumor progression rate (LTP), recurrence-free survival (RFS), and overall survival (OS) were evaluated and compared during follow-up. Technical success rate of CT/MR-CEUS FI was also recorded.

RESULTS

Technical efficacy was significantly higher in the FI group than in the US group (100% vs. 86.7%, P < 0.001). The 1-, 2-, 3-, 4-, 5-, and 6-year cumulative LTP rates in the FI group were significantly lower than in the US group (3.8%, 4.9%, 6.0%, 6.0%, 7.2%, and 7.2% vs. 16.9%, 20.1%, 25%, 25%, 25%, and 25%, respectively; P < 0.001); RFS and OS were significantly higher in the FI group than in the US group (P = 0.027 and P = 0.049, respectively). The technical success rate of FI was 85.3%.

CONCLUSIONS

Intraprocedural CT/MR-CEUS FI improved the treatment effect of thermal ablation of HCC by immediately assessing treatment response and guiding supplementary ablation relative to those resulting from the use of conventional US.

Fusion Imaging of Contrast-enhanced Ultrasound With CT or MRI for Kidney Lesions

AIM

To evaluate the feasibility of ultrasound (US) computed tomography (CT) or magnetic resonance imaging (MRI) fusion imaging (FI) for localization and assessment of kidney lesions.

MATERIALS AND METHODS

Twenty-eight patients with kidney lesions previously detected on CT or MRI were included in this retrospective study. All 28 patients with kidney lesions, which were indefinable (42.9%) or hard to localize (57.1%) on gray-scale US alone, underwent FI of US with CT/MRI datasets. In 23 (82%) patients with indeterminate kidney lesions, FI including contrast-enhanced US was conducted.

RESULTS

FI was successfully performed in 25 out of 28 (89.3%) patients. FI with contrast-enhanced US was able to clarify the previously detected kidney lesions in 21 out of 23 patients (91.3%).

CONCLUSION

FI is a feasible technique for localizing kidney lesions that are hard to define by grayscale US alone and the additional application of contrast-enhanced US is useful in clarifying indeterminate CT or MRI findings.

Accuracy of a CT-Ultrasound Fusion Imaging Guidance System Used for Hepatic Percutaneous Procedures

PURPOSE

To evaluate the accuracy of a fusion imaging guidance system using ultrasound (US) and computerized tomography (CT) as a real-time imaging modality for the positioning of a 22-gauge needle in the liver.

MATERIALS AND METHODS

The spatial coordinates of 23 spinal needles placed at the border of hepatic tumors before radiofrequency thermal ablation were determined in 23 patients. Needles were inserted up to the border of the tumor with the use of CT-US fusion imaging. A control CT scan was carried out to compare real (x, y, z) and virtual (x', y', z') coordinates of the tip of the needle (D for distal) and of a point on the needle located 3 cm proximally to the tip (P for proximal).

RESULTS

The mean Euclidian distances were 8.5 ± 4.7 mm and 10.5 ± 5.3 mm for D and P, respectively. The absolute value of mean differences of the 3 coordinates (|x' - x|, |y' - y|, and |z' - z|) were 4.06 ± 0.9, 4.21 ± 0.84, and 4.89 ± 0.89 mm for D and 3.96 ± 0.60, 4.41 ± 0.86, and 7.66 ± 1.27 mm for P. X = |x' - x| and Y = |y' - y| coordinates were <7 mm with a probability close to 1. Z = |z' - z| coordinate was not considered to be larger nor smaller than 7 mm (probability >7 mm close to 50%).

CONCLUSIONS

Positioning errors with the use of US-CT fusion imaging used in this study are not negligible for the insertion of a 22-gauge needle in the liver. Physicians must be aware of such possible errors to adapt the treatment when used for thermal ablation.

Contrast-enhanced ultrasound of hepatocellular carcinoma: where do we stand?

Contrast-enhanced ultrasound (CEUS) represents a significant breakthrough in ultrasonography (US), and it is being increasingly used for the evaluation of focal liver lesions (FLLs). CEUS is unique in that it allows non-invasive assessment of liver perfusion in real time throughout the vascular phase, which has led to dramatic improvements in the diagnostic accuracy of US in the detection and characterization of FLLs, the choice of therapeutic procedures, and the evaluation of response. Currently, CEUS is included as a part of the suggested diagnostic work-up of FLLs, including in cirrhotic patients with hepatocellular carcinoma, resulting in better patient management and cost-effective delivery of therapy.

Experimental and Preliminary Clinical Study of Real-Time Registration in Liver Tumors During Respiratory Motion Based on a Multimodality Image Navigation System

Purpose:

To develop a fusion imaging system that combines ultrasound and computed tomography for real-time tumor tracking and to validate the accuracy of performing registration via this approach during a specific breathing phase.

Materials and Methods:

The initial part of the experimental study was performed using iodized oil injection in pig livers and was focused on determining the accuracy of registration. Eight points (A1-4 and B1-4) at different positions and with different target sizes were selected as target points. During respiratory motion, we used our self-designed system to perform the procedure either with (experimental group, E) or without (control group, C) the respiratory monitoring module. The registration errors were then compared between the 2 groups and within group E. The second part of this study was designed as a preliminary clinical study and was performed in 18 patients. Screening was performed to determine the combination of points on the body surface that provided the highest sensitivity to respiratory motion. Registration was performed either with (group E) or without (group C) the respiratory monitoring module. Registration errors were compared between the 2 groups.

Results:

In part 1 of this study, there were fewer registration errors at each point in group E than at the corresponding points in group C (P < .01). In group E, there were more registration errors at points A1 and B1 than at the other points (P < .05). There was no significant difference in registration errors among the remaining points. During part 2 of the study, there was a significant difference in the registration errors between the 2 groups (P < .01).

Conclusions:

Real-time fusion registration is feasible and can be accurately performed during respiratory motions when using this system.

Management of sub-centimeter recurrent hepatocellular carcinoma after curative treatment: Current status and future

Hepatocellular carcinomas (HCCs) frequently recur despite initial successful surgical resection or local ablation therapy. Diagnostic methods for small HCCs have improved with the introduction of gadoxetic acid-enhanced liver magnetic resonance imaging and diffusion-weighted imaging (DWI). Currently, sub-centimeter recurrent nodules showing typical hallmark imaging findings of HCC are frequently detected in patients with a treatment history for HCC. With five typical magnetic resonance findings, including arterial enhancement, washout on portal or transitional phase, high signal intensity on both T2-weighted image and DWI, and low signal intensity on hepatobiliary phase, sub-centimeter recurrent HCC can be diagnosed with high accuracy. Although more information is needed to determine the treatment of choice, local ablation therapy under fusion imaging and/or contrast-enhanced ultrasound guidance or cone-beam computed tomography-guided chemoembolization seem to be promising as they are effective and safe for the management of sub-centimeter recurrent HCCs.

Comparison of Combined Therapy Using Conventional Chemoembolization and Radiofrequency Ablation Versus Conventional Chemoembolization for Ultrasound-Invisible Early-Stage Hepatocellular Carcinoma (Barcelona Clinic Liver Cancer Stage 0 or A)

Objective

To compare the therapeutic efficacy between conventional transarterial chemoembolization (cTACE) and combined therapy using cTACE and radiofrequency ablation (RFA) in ultrasound (US)-invisible early stage hepatocellular carcinoma (HCC).

Materials and Methods

From January 2008 to June 2016, 167 patients with US-invisible early stage HCCs were treated with cTACE alone (cTACE group; n = 85) or cTACE followed by immediate fluoroscopy-guided RFA targeting intratumoral iodized oil retention (combined group; n = 82). Procedure-related complications, local tumor progression (LTP), time to progression (TTP), and overall survival (OS) were compared between the two groups. Multivariate analyses were performed to identify prognostic factors.

Results

There was no major complication in either group. The cTACE group showed higher 1-, 3-, and 5-year LTP rates than the combined group; i.e., 12.5%, 31.7%, and 37.0%, respectively, in the cTACE group; compared to 7.3%, 16.5%, and 16.5%, respectively, in the combined group; p = 0.013. The median TTP was 18 months in the cTACE group and 24 months in the combined group (p = 0.037). Cumulative 1-, 3-, and 5-year OS rates were 100%, 93.2%, and 87.7%, respectively, in the cTACE group and 100%, 96.6%, and 87.4%, respectively, in the combined group (p = 0.686). Tumor diameter > 20 mm and cTACE monotherapy were independent risk factors for LTP and TTP.

Conclusion

Combined therapy using cTACE followed by fluoroscopy-guided RFA is a safe and effective treatment in US-invisible early stage HCCs. It provides less LTP and longer TTP than cTACE alone.

Feasibility, efficacy, and safety of percutaneous MR-guided ablation of small (≤12 mm) hepatic malignancies

BACKGROUND

Percutaneous tumor ablation is commonly performed using computed tomography (CT) or ultrasound (US) guidance, although reliable visualization of the target tumor may be challenging. MRI guidance provides more reliable visualization of target tumors and allows for real-time imaging and multiplanar capabilities, making it the modality of choice, in particular if lesions are small.

PURPOSE

To investigate the feasibility, technical success, and safety of percutaneous MR-guided ablation (RFA n = 27 / MWA n = 16) of small (≤12 mm) hepatic malignancies.

STUDY TYPE

Retrospective case study.

POPULATION

In all, 45 patients (age: 61.1 ± 11.8) with hepatic malignancies and a lesion diameter of ≤12 mm scheduled for percutaneous MR-guided tumor ablation based on a tumor board decision were included.

FIELD STRENGTH

A 1.5T MR system was used for planning, targeting, and monitoring.

ASSESSMENT

Feasibility assessment included the detection of the target tumor, tumor delineation during MR-fluoroscopy guided targeting, and the number of attempts needed for precise applicator placement. Technical success was defined as successful performance of the procedure including a safety margin of 5 mm. Safety evaluation was based on procedure-related complications.

STATISTICAL TEST

Frequency.

RESULTS

Tumor ablation (mean diameter 9.0 ± 2.1 mm) was successfully completed in 43/45 patients. Planning imaging was conducted without a contrast agent in 79% (n = 37). In 64% (n = 30), the target tumors were visible with MR-fluoroscopy. In six patients (13%), planning imaging revealed new, unexpected small lesions, which were either treated in the same session (n = 4) or changed therapy management (n = 2) due to diffuse tumor progress. Postprocedural imaging revealed a technical success of 100% (43/43), with no major complications. During follow-up, no local tumor progression was observed (mean follow-up 24.7 ± 14.0 months) although 28% (12) patients developed new hepatic lesions distant to the ablation zone. No major complications were observed.

DATA CONCLUSION

MR-guided ablation is a feasible approach for an effective and safe treatment of small hepatic malignancies.

LEVEL OF EVIDENCE

4 Technical Efficacy: Stage 4 J. Magn. Reson. Imaging 2019;49:374-381.

Development of a robust MRI fiducial system for automated fusion of MR-US abdominal images

We present the development of a two‐component magnetic resonance (MR) fiducial system, that is, a fiducial marker device combined with an auto‐segmentation algorithm, designed to be paired with existing ultrasound probe tracking and image fusion technology to automatically fuse MR and ultrasound (US) images. The fiducial device consisted of four ~6.4 mL cylindrical wells filled with 1 g/L copper sulfate solution. The algorithm was designed to automatically segment the device in clinical abdominal MR images. The algorithm's detection rate and repeatability were investigated through a phantom study and in human volunteers. The detection rate was 100% in all phantom and human images. The center‐of‐mass of the fiducial device was robustly identified with maximum variations of 2.9 mm in position and 0.9° in angular orientation. In volunteer images, average differences between algorithm‐measured inter‐marker spacings and actual separation distances were 0.53 ± 0.36 mm. “Proof‐of‐concept” automatic MR‐US fusions were conducted with sets of images from both a phantom and volunteer using a commercial prototype system, which was built based on the above findings. Image fusion accuracy was measured to be within 5 mm for breath‐hold scanning. These results demonstrate the capability of this approach to automatically fuse US and MR images acquired across a wide range of clinical abdominal pulse sequences.

Percutaneous US/MRI Fusion-guided Radiofrequency Ablation for Recurrent Subcentimeter Hepatocellular Carcinoma: Technical Feasibility and Therapeutic Outcomes

Purpose To evaluate the technical feasibility and therapeutic outcomes of percutaneous US/MRI fusion-guided radiofrequency ablation (RFA) of recurrent subcentimeter-sized hepatocellular carcinomas (HCCs). Materials and Methods For this retrospective study, between January 2012 and December 2014 a total of 194 planning US examinations were performed in 186 patients (159 men and 27 women; mean age, 61.1 years ± 10.0 [standard deviation]) for newly developed subcentimeter recurrent HCCs. These recurrent HCCs were defined as hypervascular nodules (>5.5 mm and <10 mm) with typical MRI findings of HCC. The study assessed how often US/MRI fusion-guided percutaneous RFA was deemed technically feasible at planning US examination (the feasibility rate) and the therapeutic outcomes after RFA, including the rates of technical success, technique efficacy, local tumor progression (LTP), and major complications. Cumulative LTP rates were estimated with the Kaplan-Meier method. Results The feasibility rate of percutaneous RFA at planning US examination was 65.7% (138 of 210 HCCs). The most common reason for RFA infeasibility was that an index tumor was inconspicuous at US. Among 138 subcentimeter HCCs feasible for RFA, 125 lesions underwent percutaneous RFA. The rates of both technical success and technique efficacy were 98.4% (123 of 125). The cumulative LTP rates at 1, 2, and 3 years were 3.6%, 5.4%, and 7.4%, respectively. The major complication rate was 2.5% (three of 119). Conclusion Percutaneous US/MRI fusion-guided radiofrequency ablation (RFA) was feasible in approximately two-thirds of subcentimeter recurrent hepatocellular carcinomas (HCCs). Percutaneous US/MRI fusion-guided RFA is a safe and effective treatment modality for patients with subcentimeter recurrent HCCs.

Percutaneous Radiofrequency Ablation of Small (1-2 cm) Hepatocellular Carcinomas Inconspicuous on B-Mode Ultrasonographic Imaging: Usefulness of Combined Fusion Imaging with MRI and Contrast-Enhanced Ultrasonography

PURPOSE

To assess usefulness of adding contrast-enhanced ultrasonography (CEUS) to fusion imaging (FI) for percutaneous radiofrequency ablation (RFA) of hepatocellular carcinomas (HCCs) inconspicuous on FI alone. Therapeutic outcomes of RFA under CEUS-added FI guidance for HCCs inconspicuous on FI alone were also evaluated.

METHODS

This prospective study was approved by the institutional review board and informed consent was obtained from all patients. Planning US was performed with FI for 126 patients with a single HCC (1-2 cm) to evaluate the feasibility of RFA by grading lesion conspicuity score using a four-point scale. RFA was performed under CEUS-added FI guidance for HCCs inconspicuous on FI alone. We evaluated how many HCCs initially inconspicuous on FI became conspicuous after adding CEUS. After CEUS-added FI-guided RFA, therapeutic outcomes including rates of technical success, primary technique efficacy, major complications, and local tumor progression were assessed.

RESULTS

After adding CEUS, 90.5% (19/21) of all tumors initially inconspicuous on FI became conspicuous, thus enabling direct targeting for RFA. Technical success and primary technique efficacy rates were 94.7% (18/19) and 100% (19/19), respectively. No major complications were observed after RFA. Cumulative local tumor progression rates after RFA were estimated to be 5.3%, 10.8%, and 10.8% at 1, 2, and 3 years, respectively.

CONCLUSION

Adding CEUS to FI is useful for improving the conspicuity of HCCs inconspicuous on FI alone, thus enabling successful percutaneous RFA with excellent therapeutic outcomes.

Recent Advances in the Image-Guided Tumor Ablation of Liver Malignancies: Radiofrequency Ablation with Multiple Electrodes, Real-Time Multimodality Fusion Imaging, and New Energy Sources

Radiofrequency ablation (RFA) has emerged as an effective loco-regional treatment modality for malignant hepatic tumors. Indeed, studies have demonstrated that RFA of early stage hepatocellular carcinomas can provide comparable overall survival to surgical resection. However, the incidence of local tumor progression (LTP) after RFA is significantly higher than that of surgical resection. Thus, to overcome this limitation, multiple electrode radiofrequency (RF) systems that use a multi-channel RF generator have been developed, and they demonstrate better efficiency in creating larger ablation zones than that using the conventional RFA with a single electrode. Furthermore, RFA with multiple electrodes can allow the “no-touch” ablation technique which may also help to reduce LTP. Another technique that would be helpful in this regard is multi-modality-ultrasound fusion imaging, which helps to not only more accurately determine the target lesion by enabling the RFA of small, poorly visible or invisible tumors, but also improve the monitoring of procedures and determine the appropriateness of the ablation margin. In addition, new energy sources, including microwave and cryoablation, have been introduced in imaging-guided tumor ablation. In this review, these recently introduced ablation techniques and the results of the most current animal and clinical studies are discussed.

Active contour configuration model for estimating the posterior ablative margin in image fusion of real-time ultrasound and 3D ultrasound or magnetic resonance images for radiofrequency ablation: an experimental study

Purpose

The purpose of this study was to evaluate the accuracy of an active contour model for estimating the posterior ablative margin in images obtained by the fusion of real-time ultrasonography (US) and 3-dimensional (3D) US or magnetic resonance (MR) images of an experimental tumor model for radiofrequency ablation.

Methods

Chickpeas (n=12) and bovine rump meat (n=12) were used as an experimental tumor model. Grayscale 3D US and T1-weighted MR images were pre-acquired for use as reference datasets. US and MR/3D US fusion was performed for one group (n=4), and US and 3D US fusion only (n=8) was performed for the other group. Half of the models in each group were completely ablated, while the other half were incompletely ablated. Hyperechoic ablation areas were extracted using an active contour model from real-time US images, and the posterior margin of the ablation zone was estimated from the anterior margin. After the experiments, the ablated pieces of bovine rump meat were cut along the electrode path and the cut planes were photographed. The US images with the estimated posterior margin were compared with the photographs and post-ablation MR images. The extracted contours of the ablation zones from 12 US fusion videos and post-ablation MR images were also matched.

Results

In the four models fused under real-time US with MR/3D US, compression from the transducer and the insertion of an electrode resulted in misregistration between the real-time US and MR images, making the estimation of the ablation zones less accurate than was achieved through fusion between real-time US and 3D US. Eight of the 12 post-ablation 3D US images were graded as good when compared with the sectioned specimens, and 10 of the 12 were graded as good in a comparison with nicotinamide adenine dinucleotide staining and histopathologic results.

Conclusion

Estimating the posterior ablative margin using an active contour model is a feasible way of predicting the ablation area, and US/3D US fusion was more accurate than US/MR fusion.

Automatic image fusion of real-time ultrasound with computed tomography images: a prospective comparison between two auto-registration methods

Background A major drawback of conventional manual image fusion is that the process may be complex, especially for less-experienced operators. Recently, two automatic image fusion techniques called Positioning and Sweeping auto-registration have been developed. Purpose To compare the accuracy and required time for image fusion of real-time ultrasonography (US) and computed tomography (CT) images between Positioning and Sweeping auto-registration. Material and Methods Eighteen consecutive patients referred for planning US for radiofrequency ablation or biopsy for focal hepatic lesions were enrolled. Image fusion using both auto-registration methods was performed for each patient. Registration error, time required for image fusion, and number of point locks used were compared using the Wilcoxon signed rank test. Results Image fusion was successful in all patients. Positioning auto-registration was significantly faster than Sweeping auto-registration for both initial (median, 11 s [range, 3-16 s] vs. 32 s [range, 21-38 s]; P < 0.001] and complete (median, 34.0 s [range, 26-66 s] vs. 47.5 s [range, 32-90]; P = 0.001] image fusion. Registration error of Positioning auto-registration was significantly higher for initial image fusion (median, 38.8 mm [range, 16.0-84.6 mm] vs. 18.2 mm [6.7-73.4 mm]; P = 0.029), but not for complete image fusion (median, 4.75 mm [range, 1.7-9.9 mm] vs. 5.8 mm [range, 2.0-13.0 mm]; P = 0.338]. Number of point locks required to refine the initially fused images was significantly higher with Positioning auto-registration (median, 2 [range, 2-3] vs. 1 [range, 1-2]; P = 0.012]. Conclusion Positioning auto-registration offers faster image fusion between real-time US and pre-procedural CT images than Sweeping auto-registration. The final registration error is similar between the two methods.